.\"
.\" Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
.\" Copyright (c) 1999 Tama Communications Corporation. All rights reserved.
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.Dd August 7, 2022
.Dt REL2ABS 3
.Os
.Sh NAME
.Nm rel2abs
.Nd make an absolute path name from a relative path name
.Sh SYNOPSIS
.Ft "char *"
.Fn rel2abs "const char *path" "const char *base" "char *result" "size_t size"
.Sh DESCRIPTION
The
.Fn rel2abs
function makes an absolute path name from a relative path name
.Fa path
based on a directory
.Fa base
and copies the resulting path name into the memory referenced by
.Fa result .
The
.Fa result
argument must refer to a buffer capable of storing at least
.Fa size
character

The resulting path name may include symbolic links.
.Fn abs2rel
doesn't check whether or not any path exists.
.Sh "RETURN VALUES"
The
.Fn rel2abs
function returns absolute path name on success.
If an error occurs, it returns
.Dv NULL .
.Sh EXAMPLES
    char result[MAXPATHLEN];
    char *path = rel2abs("../../src/sys", "/usr/local/lib", result, MAXPATHLEN);

yields:

    path == "/usr/src/sys"

Similarly,

    path1 = rel2abs("src/sys", "/usr", result, MAXPATHLEN);
    path2 = rel2abs(".", "/usr/src/sys", result, MAXPATHLEN);

yields:

    path1 == "/usr/src/sys"
    path2 == "/usr/src/sys"
.Sh ERRORS
The
.Fn rel2abs
function may fail and set the external variable
.Va errno
to indicate the error.
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa base
directory isn't an absolute path name or the
.Fa size
argument is zero.
.It Bq Er ERANGE
The
.Fa size
argument is greater than zero but smaller than the length of the pathname plus 1
.El
.Sh SEE ALSO
.Xr abs2rel 3
.Sh AUTHORS
.An Shigio Yamaguchi (shigio@tamacom.com)
